Code-call system



Je 194s.

O. BLYHOLDER CODE-CALL SYSTEM Sheets-Sheet 1 y Filed Jan. 24, 1944 Fume 8, E48. o. BLYHOLDER 2,442,947

CODE-CALL SYSTEM lig June i948. o. BLYHoLDER CODE-CALL SYSTEM 7 sheets-sheet s Filed Jan. 24, 1944 m: r f n, w

.ww YE LEMAN W bank mknk J. mmh. humm.

www1

nqhnw Mksm ,RMN hunk EQ /G/T COUNTER Jun@ 3948 "0. BLYHOLDER 2,442,947

CODE-CALL SYSTEM File Jan. 24. 1944 7 sheets-sheet 4 NPULSE COQ/NTE?? g @T-wf /npl/L sE sas/5,9470@ June 8, i948. o. BLYHOLDER CODE-CALL SYSTEM 7 Sheets-Sheet 5 Filed Jan. 24, 1944 O. BLYHOLDER Jun@ 3, i948.

CODEGALL SYSTEM '7 Sheets-Sheet Filed Jan. 24, 1944 mv NQ t w .lune 8, H948. o. BLYHOLDER CODE-CALL SYSTEM 7 Sheets-Sheet 7 Filed Jan. 24, 1944 M Q n v m Patented June 8, 1948 2,442,941v conn-CALL sYs'rM orlando Blyholaer, chicago, nl., assignma xellogg Switchboard and Supply Company, Chlcago. lll., a corporation' of Illinois Application January 24, -1944, Serial No. 519,55@

This invention relates to code-call systems such as are used in industrial establishments, or the like, to page designated persons .who may be away from their desks. oinces, or stations.

GENERAL DESCRIPTION In a code-call system of the type under consideration, a. register-sender transmits impulses, over a common signalling line to appropriately located signalling devices, according to preassigned code numbers.

'I'he main object of the invention is the provision of a code-call system of the general type outlined above which is reliable in operation and economical to manufacture. 'v

A specific object of the invention is to provide a code-call system of the foregoing type in which the register-sender transmits code numbers containing avariable number of code digits. each of which has a variable value, in which the interdigit spacing is independent of the number of impulses in the concerned digits. and in which the internumber spacing is independent of the,

number of digits 4and. the respective values thereof.

A further specific object is to provide a codecall system .of the foregoing type in 'which the register-sender comprises a groupy of suitably interconnected relays. Y

A still further specific object is to provide a system in which a number of control stations may be used without mutual interference.

Features of the invention are that (1) an impulse counter (consisting of a group of counting relays) counts the impulses of any transmitted digit, being used over and over for this purpose; (2) a digit counter (a group of relays) is controlled by the impulse counter to count the transmitted digits, associating the impulse counter each time Vwith the next successive register portion; (3) the impulse counter introduces a uniform interdigit space by counting an untransmitted impulse on each digit cycle of operations;

(4) the digit counter introduces a uniform internumber space bycausing the impulse counter to perform -a blank digit cycle of operations between numbers, during which no impulses are transmitted to the signal line; (5) an alarm sisnsl, controllable from a fire alarm box (for example) and from an alarm key, takes-precedence over any other signal being transmitted; and (6) the system maybe operated when desired to inform a watchman or other person on the premises of the location oi an entrance at which a push button has been actuated. f

A special feature of the invention is that .th

112 claims. (ci. 177-380) relays of the impulse counter comprise only those necessary to the impulse-counting operation, and the relays of the digit counter comprise only those necessary to the digit-counting operation. the counting relays of these devices performing all switching operations necessary to secure the transmission of the recorded number of digits of the respective values recorded.

A further special feature is that. while the termination of the number-transmitting operation is under the control of the operator, the terminating act, whenever performed, is automatically nullied until any number being currently transmitted has been iully transmitted,

whereby the act of termination does not abbre-y viate such number.

Other objects and features of the 'invention will become more apparent upon a further pe- Fig. 2. parts 1 and '2, shows a second embodlment of the invention. wherein locking-type convtrol keys are employed.V rendering the use of register relays unnecessary, and wherein modiiiedcircuit arrangements are employed to control the impulse'counter:

Fig. 3 shows a modification of the register- 4portion of Fig. 2, the locking key set belng'replaced by a telephone type calling device and suitable registers: y

Fig. 4 is a chart giving the time of operation and release of the counting relays of the impulse,

and digit counters of Fig. l. with respect to generated and transmitted impulses;

Fig. 5 shows how the sheets on which Fig. 1 are drawn'- should be assembled: and

Fig. 6 shows how the sheets on which Fig. 2

are drawn should be assembled.

Arrsaarus or nous: 1

The recording relays KI to KIS are associated respectively with the fifteen digit keys of either key set. i f

Cham-control relay CC'is common to the two key sets, and is interconnected with chain relays CI and C2, individual respectively to the key sets KSI and KS2. For each additional'key set desired, an additional relay similar to CI and C2 may be provided. y

The control relays shown in parti otFig. 1 include the start relay ST; relays GI to G4, interconnected to serve as an impulse generator; relays 10, 1E, and Il to It, interconnected to serve 4 as an impulse counter; relays DO, DE, and DI to DI, interconnected to serve as a digit counter: and repeating relay RR, which repeats impulses to the common signalling line-having signal devices such as SD connected thereto.

Relays I to 5, part 3 of Fig. 1, comprise the entrance group. Each relay may be associated with a different entrance at which there is an outsidestart push button such as |2| to be controlled by the visitor and an inside stop button |22 to be controlled by theperson admitting the visitor.

- 'I'he equipment in the' upperlett-hand corner i of Fig. 1, part 1, is alarm control equipment, comprising contact, signal, and relay devices |00 to 'Y The apparatus ofv Fig. 2 includes a key set illus-v trated diagrammatically at KSI and a duplicate key set indicated at KS2. ,'Key, set KSI includes a signal 'lamp-2li, non-locking start and release keys S and R',f and three sets of locking digit keys 2|3 to 2|- 5. Since th'ediait keys of KSI are of the locking type. they may be used to retain the recordyot thedigit information set up thereon, whereby recording relays .similar to KI to- `KIS 'of Fig.' `1' arenotnecessary inthe arrange-V ment o f. Fig. 2.

'Relays ce'. cl'. and czfare infimetion tothe vcorresponding relays or Fig. 1.

The relays shown-above the 'broken-line 3'3 i extending acrosspart 1 ofFlg. 2 correspond'in function tothe .similarly designated relays, of

.Fig.`1, -except for` modiilcations which will be broughtout in the detaileddescriptionto `follow.

j ng. a news-sneemtauon-ofthefaparatus of r Fig. 2 ,shown below .broken linev 3-3 extending acrosspartlthereoif. '1' t In Fig. 3, -keysets vXSI.' and Szfjarereplaced spond respectivelytothe keys R S' of Fig.

tively in. general function to rlay CC',' C|',l.and cz'ofFlg.2.--

'Iheremaining apparatus'ot Fig-..3 constitutes equipmentresponsive to trains of transmitted from either control'ktation. RI to R3 are provided to recorduch trains-ot im' pulses. Each such register 'may'conprise-a `magnetic impulse 'counter ofthe illustrated in 4 John I. Bellamy, Serial No. 493,312, tiled July.2, 1943.

Relays IMP, TRI, and TR2 comprise an impulse relay and two transfer relays interposed between the calling device of a connected one ofy the control stations and the registers RI to R3, for control purposes, to be later described.

DETAILED DESCRIPTION l I. From 1 IA. Calling No. 555

A detailed description of the operation of the system as shown in Fig. 1 will now be given. For this purpose, it will be assumed that the operator at key set KSI desires to transmit call No. 555, being a call number having the maximum number of digits (3) each digit being represented by the maximum number of impulses (5) Individualizing the system with key set KS1 The system must first' be individualized with the key set, K SI. .'Io this end, the start key S .is actuated and held until lamp H6 lights as a signal that the system has become individualized asdesired.

When the system is not in use, the ungrounded pole `of the common current source is connected through-the lower contacts of start relay ST, guard conductor |01, and contacts of chaincontrol relay CC. to conductor |50, whereby actuation of start key S (whose movable contact is grounded) energizes the lower winding of chain -relay CI. Relay CI thereupon operates, and

closes a self-locking circuit, 'including its own upper winding and the winding of chain-controlrelay CC; Relay-CC thereupon operates, and removes operatingpotential from conductor |50, 'thereby rendering, ineffective thestart keys S at all key sets. -The initial operating circuit of relay l 'Ct-(through its lower winding). is now open, but

relay .Cl remains operated in its self-docking cir--V cuit through its upper winding andI the winding of the operated 'remy Cc. Itis to be noted that conductor I8, over which the upper winding of any; one of the relays CI, C2, and so forth, may become. locked operated is carried throughthe chain circuit whereby only one such relay can be in a locked, operated condition at 'the Sametime, thereby'preventing the simultaneous individual- -ization of'the system with two key sets.-

At its lower. contacts, relay CI grounds conductor 15|, thereby rendering eiective the'normally ineective digit keys in key set KSI and lighting signal lamp lli.

Upon noting the lightedcondition of signal 'lamp H0, the operator may release the start key Sand proceed to actuate the digit keys of key -set KSI accordingV to the number to be called.V

m2. Recording cazziv'o. 555 l In the assumed example, the number to be lay CC. This locking circuit is closed at the right A .front-contact ofthe lower armature of relay K5. At the left front contact of the lower armature ol key K5, ground potential is'extended to start Figs. 21 to 25 of; the c-pendins ,of u. conductor i-ea, thereby starting the sending apvasias-rr paratus into operation, as will be subsequently described.

Additionally since none of the relays KI to K4 is operated, the grounding of start conductor results in the grounding of each of the normally connected rst-dlgit control conductors to 4 in group 0, thereby recording the fact that the rst recorded digit is 5.

When relay K|0 responds to the momentary actuation of key 5 of group ||4, it closes a selilocking circuit to conductor |23 at its lower contacts. lwhile at its upper contacts it extends ground potential to conductorV L of the second digit group as an indication that a second digit has been recorded. Since none of the relays K6 to K9 is operated, digit conductors l to 4 ot this group remain connected to the now-grounded start conductor |08, indicating that the second recorded digit is a 5.

When key 5 of group ||5 is momentarliy operated to secure the recordation of the third digit 5 in the called number 555, relay KIS operates and locks to conductor |23, at the same time grounding conductor L of digit group ||2 as an indication that a third digit has been recorded. With none of the relays K to Kl operated,

conductors i to il in the third digit group H2 A remain connected to the now-grounded start conductor |03, indicating that the third recorded digit is a 5.

IA3. Locking start relay ST tential from guard conductor |01, insuring that conductor cannot be reenergized with actuating potential until start relay ST is unlocked and restored.

IA4. Starting the impulse generator The impulse generator, comprising relays GI to G4, is started into operation responsive to the grounding of conductor |52. When this occurs, relay GI -operates through contacts of relay G4, following which relays G2, G3, and G4 operate in succession, the circuit of each such relay being closed at contacts of the preceding relay. When relay G4 operates, it open-circuits and restores relay Gl, whereupon relays G2, G3, and G4 restore successively, and relay G4 reconnects relay Gl.

The above cycle of operations is repeated continuously so long as conductor |52 remains grounded.

Each of the relays GI to G4 is a fast-operating relay. but is rendered slow-restoring, as by the usual copper sleeve arrangement intended to be indicated by the vertical linesdrawn slightly insidethe connes of the relay structure. Good results are obtained when a cycle of the impulse generator occupies a time interval of about one second. each of the relays Gi to G4 then requiring about one-quartersecond to restore' after its circuit is opened.

Relay G2 isA the impulse-delivery relay. It grounds impulse conductor X on operating, and

maintains this conductor grounded for about half 76 potential on conductor X.

a second. the time required for relays- Gl and G4 to operate and relays GI and G2 to restore.

nis. rransmlmngthe mma digit blank,

The sending apparatus is arranged to transmit a blank digit (no impulses on the Isignal line) preliminarily to each number transmission, The utility of this arrangement is twofold. It provides a spacing between numbers long enough to mark a clear distinction vbetween the end of one transmitted number and the beginning of the next, and it permits ample time for the previously described digit-key and recording-relay operations to become completed before the transmission of the rst digit of the first number is begun, avoiding the necessity of the operator hurrying through the second and third keying operations. v -h The placing of the rst ground impulse on conductor X by relay G2 of the impulse counter results in the closure of a circuit through contacts '2 of odd-control relay I0 of the impulse counter, the winding of the first impulse relay Ii, and the chain contacts controlled by armatures 4 of relays I2 to I5, and armature 3 of relay I6, to the ungrounded pole of the current source. Relay Il operates in this circuit and prepares at its contacts 2 a circuit for the second impulse relay I2, while at its contacts 3 it closes a self-locking circuit through the winding oi' relay I0. Relay I0 does not operate in this.

locking circuit for the time being, being shortcircuited by the initial energizing path between conductor X and the lower terminal o1' relayV Il.

When the iirst impulse on conductor X is ter-` minated, relay Il remains operated, and relay I0 operates,'in the above-noted locking circuit. Relay- I0 opens a point in the associated oddimpuise path at its contacts 2, while at its contacts it closes a. point in the associated evenrelay operating path.

As a further result of -the operation of relay .I|, the grounded conductor |52 -is extended through contacts of relay Il to conductor XI, extending to the digit counter, thereby operating the ilrst counting relay DI thereof in a circuit path similar to that above traced for relay Il of the impulse counter. Among other things, relay DI disconnects impulse conductor Y from impulse conductor Z, thereby insuring that no impulse will be transmitted from conductor X over conductors'Y and Z to relay R during transmission of the initial digit, blank now ensuing.

' Relay DI also connects grounded' conductor |52 circuit for the second counting relay I2 of the impulse counter is thereby closed, through con tacts 2 of even-control relay IE, winding of relay I2, contacts 2 of relay Il, and icontacts of relay I0. At'its armature 4, relay`I2 rst closes a-self-locking circuit through the chain contacts of the succeeding counting relays. and then opencircuits and restores relays 1| andI0. .Relay I2 also locks its lower terminal to ground, through the winding o! relay IE, itsown contacts l, contacts of the operated relay DI, and conductor |52. Relay IE does not operate for the time being, being short-circuited by the ground when the second impulse is terminated the short circuit is thereby removed from relay IE. Relay I2 remains locked operated, and relay IE opcrates in the lockingcircuit of I2. Upon operating, relay IE opens a point in the associated evenimpulse path at its contacts 2, and at contacts I it closes a point in the associated odd-relay operating path.

When the third impulse is placed on-conductor X, relay I3 operates through contacts of the restored control relay I0, its own winding and contacts of the operated relays I2 and IE. It locks itself to the source of operating potential at its armature I, and then opengcircuits and restores the operated relays I2 and IE. Additionally, relay I3 at its contact 5 closes a self-locking circiutin series with the odd-control relay I0, to ground by way of contacts 6 of the relay DI and conductor contacts 3 of relay I3 for the fourth re-v lay II.

Relays I4 and I5 operates responsive to the fourth and fth impulses, respectively, as described for relays I2 and I3, each such relay, upon operating, restoring the preceding counting relay, along with the then operated one of the control relays I0 and IE. f

At the termination o f the ith impulse on conductor X, the then operated relay I5 remains locked operated and control relay I0 again reoperates. Relays I0 and I5 are the only relays of the impulse counter then in operated condition.

When the sixth impulse is placed onconductor X. relay I6 is thereby operated, through contacts of the restored even-control relay IE, the winding of relay I6, contacts 3 of relay I5, and contacts I of the reoperated odd-control relay IIB. At its armature 3, relay I6 locks itself directly to the oper-` not lock itself operated to ground, as is the case with each of the preceding counting relays. Ac-

cordingly, whenthe sixth impulse is' terminated, relay I6 restores, thereby returning the impulse counter to its original normal ncondition. The preliminary digit blank; having a'length (about six seconds) equal 'to the time consumed by six cycles of operation of the impulse generator, has now been transmitted, and all of the relays of the impulse counter are in restored condition in readiness to reoperate as required for the transmission ofcthe digits of the recorded call number.

IAG. operation cf the digit ccuntcrv From an operational standpoint, the digit counter (comprising odd and even control relays DO and DE, and counting relays DI to DI) resembles the impulse counter, diering incidentally in that it containsonly four counting` relays in the i1 lustrated embodiment, whereas the impulse counter is illustrated as containing the previously described six counting relays II to I6.

As previously indicated, the digit counter is controlled over impulse conductor XI. A single impulse is delivered over conductor XI to the digit' counter for eachcomplete operation of the im."f pulse counter. YAs previouslyfnotedftheimnil/se over the associated conductorL. It may be notY ed that relays D3 and DO' are then the. only re- 8 to' the digit counter is begun upon the closure of contacts I of'relay I2. This impulse is continued at contacts 2.of the succeeding counting relays I2 to I6 so long as any one of them is in operated condition, until the operation of the impulse counter is terminated. upon the restoration of the last counting relay thereof to operate.

Upon the initial grounding of conductor XI,

relay DI of the digit counter operates as previously noted, through contacts 2 of relay DO, the winding of relay DI and-the contact chain including normally closed contacts controlled by armatures 2 of relays D2 and D3, and armature I of relay D4.

Relay DI' locks itself operated through odd-control relay DO, which relay operates in the locking circuit of relay DI responsive to the ungrounding of conductor XI upon the termination of the transmission of the initial digit blank.

Relay DO, besides disconnecting the associated odd-impulse branch from conductor XI at its contacts 2, places energizing potential on the associated even-relay operating conductor at its contacts I. v

When the .impulse counter starts its second cycle of operations, during which it transmits the Vrst digit ofthe recorded numbenas will be subsequently explained, relay II thereof again grounds conductor XI, and this conductor is maintained continuously grounded at contacts of f one or another of the succeeding relays of the impulse counter until such transmitted.

'I'he second grounding of conductor XI results in the closure of an operating circuit, through contacts 2 of even-control relay DE, the winding of Relay D2 also locks itself to ground through -the even-control relay DE and its own contacts 2, provided locking conductor L of the second digit group III has been grounded, responsive to f the operation of one or another of key relays K6 to KIIl` of the second digit group. In this. event, when the first digit impulse transmission has been completed, and conductor VXI is consequently again ungrounded, Vdigit-counterrelay D2 remains operated, and relay DE operates in the abovenoted locking circuit thereof.v

At the beginning of `the transmission of the second recorded digit, conductor XI' is again grounded, whereupon the operating` circuit is closed, through contacts# of the restored relay DO, the Winding of relay D3, and contacts I of the relays D2 and DE. Relay D3 thereupon op- A crates, looking itself to the operatechain at its thevrelays KII .to KIS) to indicate that a'. third digit has beenrecorded, relay D3 remains locked operated, and relay DO reoperates in the lockmg circuit, through contacts a 4cf' relay Da and i lays of the'digit counter in operated condition.

groundsconductorsxi, relay D4V of thefdigit digit has been completely.

counter is operated, ugh contacts 2 ci the restored relay DE, the winding or relay and contacts I oi relays D3 and D0. Relay D4 thereupon locks itself directly to the source of operf amasar normal condition, in preparation for startingl IA?. Transmitting the ,d1-st recorded' digit 5 The next impulse delivered to impulse conductor X by the impulse generator, following the described clearing out of the impulse counter at the end of the transmission of the preliminaryI number-spacing digit blank, results in the reoperation in the described manner of vcounting relay li of the impulse counter. At this time, conductor Xi of the digit counter is again grounded, thereby causing the described operation of relay D2 of the digit counter to occur, :followed immediately by the restoration of relay DE.

Relay Di, at1 its armatures d to l, disconnects grounded conductor 52 from .the locking armatures 5 of relays I2 to I5 leaving such armatures supplied with ground potential only by way of conductors i to d of the rst digit group im, and contacts of the operated relay D2.

In the assumed example, each of the conductors d of group HB is grounded, whereby locking potential is supplied for the rst digit locking of each or" the relays i2 to i5 of the impulse counter. Accordingly, the operation of the impulse counter proceeds as previously described. That is, relays I2 to I6 operate successively following the operation of relay Il. each such relay open-circuiting and restoring the preceding counting relay. Relay I6, being unable to lock, restores at the end of its operating impulse, again bringing the impulse counter to normal condition in readiness for the transmission of the second digit of the number. l

Through contacts i of relays I2 to I6, conduct'or Y receives nve impulses from conductor X duringthe transmission of the rst recorded digit, 5. As distinct from the operations occurring during the transmission of the preliminary digit blank, relay DI of the digit counter is not then in operated condition. Accordingly, conductor Y is connected to conductor Z, whereby I the five impulses received'at conductor Y pass over conductor Z to the repeating relay RR. Relay RR accordingly repeats the ve impulses of the rst digit over the illustrated signal line. to the signal devices such as SD connected thereto.

It is to be noted that no impulse is transmitted to the signal line during the impulse period in which the first counting relay Il of the impulse counter is operated, for relay II has no contacts for joining impulse conductors X and Y. This time of one impulse period, required for the operation of relay I|, is employed as an interdigit time interval to provide a time separation between successive digits of the same number. -This interval is conveniently introduced just preceding each digit transmitted.

las. Traasmittingthe second recodeddgit 5 I Withthe impulse counter having cleared out as previously describediollowing the transmission oi.' the rst recorded digit, conductor Xi extending to the digit counter is ungrounded to cause operations to occur therein as previously described. pursuant to its counting operation.

When relay Ii of the impulse counter next responds' to count the inter-impulse interval preceding the transmission of the second recorded digit, itagain grounds impulse conductor Xi, whereupon counting relay D3 oi the digit counter operates as previously described, followed immediately by the restoration of relay D2. 'The locking armatures 5 of relays I2 to I5 are thereby disconnected from conductors ito 5 of the rst digit group iid and transferredto the respective conductors i to d of the second digit group lil, each of which latter conductors is grounded as previously pointed out. Accordingly, the operation of relay Ii oi the impulse counter pursuant to the transmission of the second recorded digit is followed by the successive operation of relays I2 to It, relay l5 restoring at the end of its concerned operating impulse, again bringing the-impulse counter to normal position,

Five impulses are transmitted over the sending line during the second-digit operation oi' the impulse counter, through contacts i of relays I2 to It, as described in connection with the transmission of the rst digit 5.

me. rmnsmittmg the mira recorded digit 5 When relay Ii of the impulse counter reoperates at the beginning of the third-digit operation of the impulse counter, the consequent regrounding of conductor XI leading to the digit counter causes relay D4 thereof to operate as previously IA10. Repeating the number transmission When relay IGVof the impulse counter restores at the end oi the transmission of the finalimpulse in the third digit 5 of the called number 555, and again ungrounds conductor XI leading to the digit counter, the ilnal counting relay Dd of thedigit counter `thereupon restores, again bringing the digit counter into normal condition, coincident with the resumed normal condition of l the impulse counten The foregoing operations are therefore repeated as described for so long a time as start conductor |08 remains grounded.

lAll. Clearing out When the recorded called code number has been transmitted aidesired number of times, the operator at the key set KSI actuates the release key R until signal lamp IIB becomes extinguished.

Aotuation of key R applies ground potential to conductor H8, thereby holding chain relay CC operated but short-circuiting the upper winding of any operated one of relays CI C2, and so forth. In the present example, the operated and locked relay is C I. l' This relay restores responsive to the short-cirouitng of its upper winding. At itsA lower armature. relay-CI removes ground potential from the key-supply conductor I 5l of the key set XSI, thereby rendering the keys ill to llt again inehectual. and extinguishing the signal lampill.\

Upon noting that signal nmp m has become extinguished, the operator may release `the key R, whereupon chain-contrairelay CC restores again joining conductor |50 with guard. conductor |01, and removing the direct ground connection from conductor 123. e Y

If the `sending apparatus shown in part l of Fig. 1 is at themoment in the act of transmitting the' digit blank, relay Dl of the digit counter is in operated condition and the clearing-out opera- 12` and third recorded digits are transmitted. The lapse oi time indicated bythe spacingjbetween lines a and b is occupied by the transmission oi the preliminary digit blank, the primary purpose ations pursuant to transmitting number 555, while tion immediately follows the described opening of the ground connection'te conductor' |23. On the other handit the impulse-sending apparatus is at some other portion of a number-transmitting cycle, start conductor is connected, at the hack contact of armature 3 ot the then restored relay DI, to conductor H2, grounded at the front contact of the inner armature'oi start relay ST. In this event, the sender-controlled ground potential on conductor |08 -passes through the right iront contact oi, the lower armature of the operated one of the rst digit-recording relays KI to K (relay K5 in the assumed example) to conductor |23, thereby maintaining' ground potential on conductor |28 to maintain the operated key relays in locked condition for the time being.

` When the impulse sending apparatus next reaches its previously describeddigit-blank position. and relay DI of the digit counter reoperates as described, the consequent disconnection of conductor |68 from the grounded conductor |52 at the back contact of armature 3 o! relay DI permits start relay ST. and any locked ones of the key relays KI to KI l..to restore. Upon restoring.

relay ST removes ground potential from conductor |52, thereby terminatingthe cyclic operathe lighter intermediate portions of line X ,represent the respective' ter-impulse intervals.

Lines Il to Il; re er respectively to relays Il to I8 of the impulse counter, Fig. l. Heavy portions ot each such line indicate the time intervals during which the concerned relay is' operated, the light portions indicating the time intervals during which the concerned relay is inrestoredcondition. From this chart, it is clear that relays Il to Il respond respectively at the beginning ot impulses' l to 6 on conductor X; relays I I to Il restore respectively at the beginning of impulses 2- toi on conductor X (being heldl locked operated during the concerned inter-impulse interval, as pre-l viously described); and that-relay I6 restores at the end oi' the sixth impulse, there being no locking circuit for such relay. vThe restoration o! relaylt at the end oi the sixth impulse brings the impulse counter back to normal condition,

- wherein no relays therein are operated, as previously explained. y l

' The chart of Fig. 4 further indicates that the operations of relays Il to I8 illustrated between digits of the called number 555.

tion of relays Gl to G4 comprising the impulse generator. Any operated ones of the relays of the impulse and digit counters now restore for the lack of operating and locking potential, and the entire system is in' normal condition. f

With start relay ST and chain-control relay CC restored, energizing potential is reapplied to conductor il, permitting operation to occur of one or another of the chain relays CI, C2, and so forth. to individualize the.' recording and sending Line Y of Fig. 4 indicates the impulses transmitted by way of conductor X to conductor Y of Fig. 1. The chart shows that "conductor Y receives five impulses coincident with the second to sixth impulses=placed on conductor X during.

apparatus with any key set at.which the start key is operated as previously described.

As a result of the holding arrangement just described, the operated recording relays are held, -1

and the-sending apparatus continues to function, until any partially transmitted number has been completely transmitted, before the equipment is permitted to clear out. Mutilation of the ilnal transmission of a series of transmission of a number is thereby avoided.

' IA12. Explanatory chafa- Figure 4 will be observed that the ilrst impulse on.con

ductor XI begins at the beginning of the ilrst denotes the beginning of the next similar time.

period, during which the same cycle of operations is repeated; vvertical line b denotes the beginning of the time interval during which' the first reterminated when relay I8 restores at the end of corded digit of the number is transmitted; and\ vertical lines c and d denote the beginning of the respective time intervals during which the second each of the -four time intervals ab, bc, etc. That is, conductor Y receives all impulses transmitted to conductor X', except the ilrst, transmitted in a digit interval, such first impulse being the one which operates relay II and nt being transmitted to conductor Y because relay Il has no contacts thereon for interconnecting conductors-Xand Y.`

Line Z of Fig. 4 represents the impulses transmitted over conductor Z ot Fig. lto repeating relay RR.. Line Z shows that no impulses reach conductor Z'of Fig. 1 during transmission of the digit blank, but all impulsesl transmitted to conductor Y during the respective recorded-digit intervals reach conductor Z. The absence of impulses on conductor Z duringtransmission of the internumber-spacing digit blankis secured by contacts I of relay DI of the digit counter, which are then open. as previously explained.

Line XI of Fig. 4 indicates the impulses delivered over conductor Xi to the digit counter. It

impulse on conductor'X and continues until the end of the sixth impulse on conductorX. 'Ihis results from thefact that` each ofthe relayaII to I8 grounds conductor X|,-thus providing the desired long impulse thereon, which impulse is any'cycle of operations ofthe impulse'counter, As shown by the chart, a further similar impulse is delivered toc'onductorXi during each 'succeeding digit interval.

digit apply to other values for the third digit, in

that any one of the relays KII to KM can be operated in place of relay KIE, disconnecting one or another ofthe conductors I to of the third digit group II! to give the third recorded digit a correspondingly reduced value.

Since the impulse counter, upon being cleared out, immediately starts a new cycle oi operations.

V the'lnterdigit spacing is independent of the numon conductor Xi; that each of the relays D2 and D3 remains operated until the next succeeding digit-counter relay operates; and that relay Dt restores at the end of the fourth impulse on conductor XI, returning the digit counter to normal condition in readiness for the starting of a new cycle of operations thereof.

E. Talsmitting other three-digit numbers Any one of the three digits of a.threedigit transmitted number can have any value from 1 to 5, the value being determined according to which of the iive keys in the concerned one of groups i I3 to l i5 is operated to record such digit. resulting in the operation of the corresponding one of the associated group of key relays. For example, if the rst digit of the number is 4 instead of 5, relay K5 is operated instead of relay K5. Conductor i of the rst-digit group Hi is then disconnected from conductor w8, conductors i to 3 of the same group being left connected. In this event, when the impulse counter goes through the rst-digit cycle of operations, with relay D2 of the digit counter in operated condition, the absence of ground potential on'conductor t of group IIIi deprives relay I5 of locking potential. Accordingly, relay I5 restores at the end of the impulse which operated it, and consequently at the end of the transmission of the fourth impulse in the iirst transmitted digit of the number. The restoration of relay I5 at this time clears out the impulse counter to prepare it for a new cycle of operations, and removes ground potential from conductor XI to prepare the digit counter for advance to the second-digit position.

Similarly, if any one of the relays KI to K3 is operated instead of either relay KB or K5, the corresponding one of conductors I to 3 in. group III) is ungrounded, causing the corresponding one of the impulse counter relays I2 to I4 to fail to lock operated during the transmission of the rst recorded digit in the number. The current cycle of operations of the impulse counter is accordingly abbreviated tothe transmission of one impulse, two impulses or three impulses, to relay RR, dependent upon which of the three digit values under consideration has been 'recorded for the first digit. I

Similarly, if the second digit has a value of from. 1 to 4, the corresponding one of the key relays K5 to K9 is operated in place of relay KIIl. In this event, any operated. one of the concerned relays grounds the locking conductor L as described for relay KIIl, and additionally ungrounds the concerned one of conductors I to 4 in the second digit gr up I'II. Accordingly, the concerned one of co nting relays I2 to `I5 fails to lock operated during the transmission of the second recorded digit (with digit-counter relay D3 in operated condition) terminating the second-digit counting and sending operatlon.correspondingly sooner than in the example first described.

From the foregoing it will be appreciated thatV the remarks concerning other values of the second y ber.

ber of impulses in the digit last counted, for the spacing interval is introduced by the time interval consumed by the operation of relay Il ahead of relay I2, impulsel transmission (over conductors Y and Z) not starting in any event until relay I2 operates, as previously described.

IC. Transmitting twodiqit unumbers -If the code number being called contains only` two digits, the key set operator operates a key of group I I3 according to the value of the'rst digit and a key of group IIE according to the value of the second digit, but fails to operate a key of group IIE. In this event, operations as previously described occur to cause transmission of the preliminary digit blank, followed by transmission of the two recorded digits of the number. The transmission of the second recorded digit of the number occurs, as described, with relay D3 of the digit counter in operated condition. In the foregoing description it was pointed out. that relay D3 locks operated through relay D0 and over conductor L in group H2, when the'number being called contains three digits. With a two-digit number recorded, conductor L of group H2 is not grounded, for none of the relays Kil to KIS is then in operated condition. In this event, relay D3 closes no locking circuit for itself (at its armature 3 and associated contact). Accordlngly. relay D3 restores responsive to the ungrounding of conductor XI, next ensuing, at the end of the second transmitted digit of the num- The restoration of D3 in this event completely clears out the digit counter for a new cycle of operations, at the beginning of which relay DI again operates to control the transmission of the internumber-spaclng digit blank, pursuant to the next cycle of sending operations.

ID. Transmitting single-digit numbers I none of the keys in groups I I4 and I I5 is operated.

whereby all relays 5K6 to KIS remain in normal position. In this event, neither of the vconductors L in groups III and I'I2 is grounded. Accordingly, when relay D2 ofthe digit counter operates to connect conductors I to il of the next digit group I'IU to the circuit conductors of the impulse counter, relay D2 'fails to lock operated because of the absence of locking ground on conductor L of digit gro'up III. As a result. when conductor XI is next ungrounded, at the termination of the first-digit counting operation of the impulse counter. relay D2 immediately restores and returns the digit counter to normal condition, whereby a new cycle of operations is commenced to immedi- IE. Regulating the nternumberspace interval The length of the internumber space interval (of the previously described digit blank) can be I 204425947 Y I".

Yreduced as desired by emitting connections between armatures "to 1 of relay DI oi the digit.

counter. For example, if the connection between armatures 4 and 5 of relayDI is severed,l the previously described locking circuit forv relay I5 of the impulse counter, during transmission of the digit blank,'is opened with the result-that l relayl does not lock during the transmission Y only ve impulse cycles instead of the six indicated in Fig. 4. y

If the connectionbetween rmatures and 6 bf relayDI is severed, relay Il of the-impulse counter fails to lock during transmission of the digit blank, in which case thel length of this spacing digit is further reduced to .four impulse cycles. n

If the connection between armatures 6 and 1 of relay DI is severed, relay I3 fails to lock, givin! the digit blank only a three-impulse length. A

Finally, if the connection between armatures 5l and 'I of relay DI is severed, only relay II of dthe impulse counter can lock operated during transmission of the digit blank, in which event 'trances The illustrated Many establishments have a number Lof venementJ is such that the watchman, on being called from any entrance. is' infomed of the identity o! such entrance. n

The entrance group of call relays comprises relays I to 5, providing for any number of entrances up to five. At each-entrance, a push button such as I2| may be provided to cause the operation of the associated entrance relay. Associated with each entrance is a normally closed stop button |22, used to unlock and restore the associated entrance relay, such as 5.

The entrance group or equipment is arranged to be placed in operative condition by the closing of a conveniently located entrance key EK,

lwhich may be closed only during nonbusiness ho s.

lllvth the key EK operated, if the start push button I2| at the entrance with which relay 5 is associated be operated, relay 5 operates and ,Y such digit consumes only the time oi the two IF. Clearing out from another'key set lThe clearing outv operations; previously de' scribed as occurringiresponsive to oper-ation of Y the releas'key R at key set KSI -may be performed at any other keyset, such as KS2, independent of with which key set the system is then individualized, for 'conductor H8, which is grounded to cause the described clearing out operation, is common to all the key sets, asindicated, and operation of release key Rat any locks to ground through its own contacts, contactsof stop button |22, and contacts of the entrance key EK. Relay 5 also closes an operating circuit for relay K5 of the rst-digit group oi recording relays, provided no other one of the relays KI to K5 is in operated condition. If no other one of the relays KI to K5 is operated, then relay K5 responds and extends its operating ground potential to start conductor |08 to start the sending equipment into operation. Since none of th'e remaining key relays K6 to K|5 is key set grounds this same conductor, A,to thereby short-circuit and restoreany operated one of the chain relays CI, C2, and so forth, This arrangement enables a key set operator who may have a more urgent code call to impress on the system to clear out the system to, that end before the system is Acleared out .bythe operator. who originated the call being currently" transmitted. Additionally, if an operator sh'ould be called away from his key-set station without clearing out, an operator at any other key set can perform the clearing-out operation.

IG. Transmittng entrance signals Referring now to the -entrance group comprising relays I to 5 (part 3 of Fig. 1) and associated equipment, the operation ofthesystem to transmit entrance signals will be described. A

In many establishments, a watchman or simllar person is on the premises continuously during non-business hours. The duties of such watch'- man ordinarily include admittance to the premises of any authorized persons.' The watchman is expected to make regular tours of the premises and is accordingly not located continuously vat Vany one station. He is accordingly conveniently called overthe general calling system, through operation of signalling devices SD.

operated, the equipment functions as previously described to transmit a single-digit number, and

the digit value of this number will be 5 when relayv K5 is the one operated, by entrance relay 5. Whenthe watchmanresponds to the entrance4 signal, he mayterminate the signalling operation and clear out the equipment-by momentarily operating push button |22, which may be conveniently located near the concerned entrance. Relay 5 is unlocked and restored by operation of button |22. opening the initial circuit of the associated relay K5, and the latter relay promptly restores, provided start conductor |08 is not at the moment held grounded by the sending equipment.y In the latter case, the restoration of relay K5 is delayed until the vsending apparatus reaches the internumber portion of its cycle, as previously described. l

It will be apparent that the other relays l to 4 of the entrance group similarly control key relays KI to K4 respectively to cause transmission of therespective call numbers 1 to 4.

The rst and second upper armatures of key relays KI to, K5, together with their associated contacts and the illustrated interchaining connections, are for the purpose of avoiding intertential is removed from conductorA |55 at the norvmally closed contacts-controlled by the second upper armature of any operated one of the relays KI toK5. v

Wh'en relay K5 is subsequently restored, .re-

sponsive to the restoration of relay 5 ae described, operating potential is replaced on conductor |155, whereupon the prepared circuit for relay Ki becomes eective, Relay Ki thereupon operates and locks operated at its rst upper armature and iront contact, again removing operating potential from conductor i 55 to prevent operation of any remaining ones of the relays K2 to K5 if a further entrance relay should become operated and locked before the watchman ha responded.

IH. Alarm operation As previously noted, the equipment illustrated in the upper left-hand corner of part 1 of Fig. 1 is provided for' the sounding of a distinctive alarm over the common code-call system, when desired. For this purpose, an alarm box such asl is provided, and any desired number of similar alarm boxes may be connected in parallel therewith. A common use for such an alarm box is to indicate that a re has broken out on the premises, or that some other emergency condition has arisen.

When the contacts of alarm box W0; close, relay responds, thereby closing a circuit through contacts of key |03 for relay 50B. Relay |06 applies ground to start conductor |00 to start the sending equipment into operation, and it directly connects conductor Z to conductor X, causing each impulse from the impulse generator to be transmitted to conductor Z. 'Ihe result is the delivery of a continuous succession of impulses to signal devices SD.

When the alarm condition is ended and the contacts of alarm box |00 have been opened. relays |05 and |06 restore successively, and the sending apparatus ceases operation responsive to the resultant removal of ground potential from start conductor |08.

Key |03 is provided to disable relay |05 in the I event that the contacts of the concerned alarm box are not promptly reopened on .the termination of the alarm condition. Upon being operated, key |03 disconnects the front contact of relay |05 from relay |06, permitting relay |08 to restore and terminate the alarm signal. Key |03 further connects the back and front contacts of relay |05 to signal lamps I0| and |02. Lamp |02 thereupon becomes lighted as a signal that relay |05 is still operated.

When the alarm circuit is subsequently restored to normal condition, permitting relay"|05 1 sires to transmit call number/555.

to restore, lamp |02 becomes extinguished and lamp |0| becomes lighted as a signal that the alarm circuit is now clear. The operator may then restore key |03, extinguishing lamp IOI and again preparing a circuit for relay I 06.

Key |04 is provided to enable the alarm condition to be initiated by a. key set operator, as from direct observation or from a telephone report. When operated, key |04 operates relay |06 with results as previously noted. Relay |06 restores when key |04 is next opened.

It will be apparent that the alarm condition. takes precedence over any other call that may be sounding, and that the sounding of the previous call is resumed on the termination of the alarm condition.

II. Fromm 2 IIA. Calling No. 555

A detailed description of the operation of the modied system shown in Fig. 2 will nowbe given, for which purpose it will be assumed that IIA1. Recording call No. 555

The operator at key set`,KS| may first record call No. 555 by operating' key 5 in each of the digit columns 2|3, 2id, and 2|5. The digit keys of this key set being' locking keys, the record of the called number is retained thereon. The key set operator will of course restore any operated ones of the remaining digit keys of the key set,

to the end that only the desired key-in each of `the columns 2|3 to 2|5 is in'operated condition.

naz. individualizar: me system. with key set KS1 The operator at key set KSI may now. operate non-locking start key S' momentarily to cause the system to become individualized with such key set. Key S' applies ground potential (obtained over ground conductor G in cable CAI) to lead O in cable CAI. The grounding of conductor O, if the system is in normal condition, closes a circuit through the operate winding of relay CI', to battery .by way oi contacts of chaincontrol relay CC', guard conductor 207, and contacts 3 of start relay ST. Upon operating, relay Cl closes aself-locklng circuit for its right-hand winding, through the winding of relay CC'. Relay CC thereupon operates and disconnects guard conductor 20T from conductor 250, thereby disabling any remaining relays C2', and so forth, from operating. Relays ClA and CC' remain operated in series thereafter. Lamp 2I6 lights in parallel with the right-hand winding of relay C I'. Relay CI' connects conductor ST in cable CAI to start conductor 208; connects digit leads I to 5 in cable CAI respectively to mark leads MI to M5;.and connects leads L2' and. L3' respectively to locking leads L2 and L3.

IIA3. .Starting` the sending operation With key 5 of digit column 2|3, and individualizing relay CI operated, a circuit for relay ST' is closed: from ground through the lower contact pair of such key 5, conductor ST in cable CAI. contacts of the operated relay CI', start conductor 208, and thence to operating potential by way of the winding of start relay ST'. At its contacts 3, relay ST removes operating potential from guard conductor 201; at its contacts I.

'conductor Xl' through contacts of relay I6' of the impulse counter. The grounding of conductor Xi' (corresponding in function to conductor Xl of Fig. 1) results in the operation of relay DI', associated with the transmission of the preliminary digit blank. At its armature .3

and front contact, relay DI' closes a self-locking' circuit through control relay DO'; to secure the operation of the latter relay when the instant impulse on conductor XI is terminated. At the back contact of its armature 3, relay DI' opens the self-locking circuit of relay ST' to permit u clearing out to occur during the transmission of any preliminary digit blank, about as described in connection with Fig. l.

m5,lrransmatmy me mainz aan blank Preparatory to the transmission of the initial digit, relay DI' oi the digit counter disconnects conductor Y from conductor Z' at its contacts I,

impulse conductor 26| by the associatedimpulse generator results in the operation of relay II' through contacts 2 of relay I0'. Relay II' closes Aa self-locking circuit at its contacts 4 to grounded conductor 209 to secure the operation of relay I at the end of the impulse on conductor 26|; at its contacts 3, it locks operating potential (through chain contacts of the succeeding count-v ing relays) on its upper terminal; at its contacts 2, it prepares to place operating potential on the upper winding terminal of the next succeeding counting relay 12'; and, at its contacts I, it joins impulse conductor X' to conductor Y', but the latter operation is of no eect at this time (during transmission of the digit blank) for conductors Y' and Z' are now disconnected at contacts I of the operated relay DI'.

When the first impulse on conductor 26| is' terminated, relay I0' operates in the locking circuit of relay Il and supplies operating potential to the upper terminal of relay I2', through contacts 2 oi relay II'.

Relay I2 operates through contacts oi relay IE', responsive to the next impulse on conductor 26|, whereupon it locks itself to conductor 209 through relay IE'; locks operating potential on its upper winding terminal through the contact chain controlled by the succeeding counting relays, at the same time open-circuiting and restoring relays II' and I0'.

When the second impulse on conductor 26| is terminated, relay IE' operates to place operating potential on the upper terminal of the third counting relay I3', by way of its own contacts I, and contacts 2 of relay I2.

Relays I3 and I4' respond respectively to the third and fourth impulses on conductor 26I, and relays I5' and I6 respond respectively to the nith and sixth impulses. Each Vsuch relay, on responding, restores the preceding counting relay, along `with the associated one of the control relays III and IE. Each of the relays II' to I5' locks operated as described for relays II and I2', but relay'IB does not lock operated independent of conductor 26|.

When relay I6' operates, besides restoring relay and the associated relay IIi'v at the con tacts controlled by its armature I, it disconnects impulse conductor XI' at its contacts 2, thereby terminating the impulse to the latter conductor. When this occurs, relay D0' operates in the locking circuit oi! relay DI to apply operating potential to the upper terminal of relay D2', through its own contacts I and contacts 2 of the operated relay DI When the sixth impulse on conductor 26| is terminated, relay IB', not having locked operated relays I5' and'IS' are effective during transmis- 20 independent of such impulse conductor, immediately restores, returning the impulse counter to its illustrated normal condition.

The preliminary digit blank, having a duration equal to six cycles of the impulse generator, has now beenl completely transmitted.

In the illustrated example, conductor DCB extends from armature'4 of relay DI' to the upper winding terminal of relay II. Ifa lesser duration is desired for ,the preliminary digit blank, conductor DCB may be disconnected from the ulper winding terminal oi relay II' and connected to the corresponding terminal of one or another of the relays I2' to I5'. Connection of conductor DCB to the upper winding terminal of relay I5', for example, reduces the duration o! the digit blank to that of two cycles of operation o! the impulse generator, for then, only counting sion of theinternumber-spacing digit lblank.

IIA5. Transmittng the first recorded digit 5 When relay I6' restores at the end oi the transmission of the preliminary digit blankfit again 'grounds conductor XI', thereby operating counting relay D2' through contacts 2 of relay DE',

the operating circuit including contacts oi 2 and I of relays DI' and D0'.

Relay D2 locks operating potential on its winding terminal at its armature 2 and front contact, at the same time open-circuiting and restoring relays DI and D0. Conductorl DCB is thereupon disconnected by relay DI'.

At its contacts 4, relay D2 connects operating pOtentiaLobtained over conductor 200 and resistor 260, to conductor DCI (digit controlrst). With the upper contacts of key 5 oi the rst column 2I3 closed, the operating potential is further extended to conductor 5 in cable CAI, and thence, through contacts of the operated chain relay CI and marking conductor M5, to the upper winding terminal of the first counting relay 'minal is supplied with operating potential over i conductor M5 'as above noted, operates through contacts of relay I0' with results substantially as above described in connection with the transmission of the preliminary digit blank. At this time, with relay DI in restored condition and conductors Y and Z' consequently reconnected, the closing of contacts I of relay Il' results in the joining of conductors X' and Z'. Accordingly, when relay G2' of the impulse counter restores to terminate the instant impulse over conductor 26|, it transmits an impulse over conductors X', Y', and Z' to repeating relay RR shown in Fig. 1.

Relays I2' to 16,' respond as previously described to the impulses respectively succeeding the one serving to operate relay Il". Conductors X' and Y are maintained connected together by contacts A conductor 26| by the impulse counter pursuant to the transmission of the'first recorded digit 5 of the called number. With conductors X' and Y again separated, no -impulse 'is transmitted to the repeating relay dlu'ing the interval between the lastnamed impulse over conductor Ztl and the next succeeding impulse thereover, whereby an interdigit space is introduced, one impulse cycle longer than the inter-impulse space, and of a length similar to that of the interdigit space introduced as described in connection with the operation of the apparatus disclosed in Fig. l.

` une. rmnsmatfng me second recorded digit Is When relay I' ungrounds conductor XI at the end of the transmission oi' the ilrst recorded digit, digit-counter relay D2' remains operated, and control relay DE' operates, over the following self-locking circuit, eective only when the number called contains a second digit: from ground over conductor G in cable CAE, the lower contacts of any operated key in column 2id (key 5 in such column in the assumed example), conductor L2',

contacts of the operated chain relay CI', seconddigit locking conductor L2, contacts 3 of the operated relay D2', winding of relay DE', winding of relay D2', and thence to operating potential through the operated armature 2 of relay D2' and chain contacts of the associated succeeding countlng relays.

Upon the restoration of the non-locking relay I6' of the impulse counter at the end of its operating impulse over conductor Esi, the consequent regrounding of conductor X i closes an operating circuit, through contacts 2 of the restored relay DO', for relayDt', by way of contacts I of relays D2' and DE. Relay D3', at its contacts 2, locks itself to operating potential through contacts of relay Dd', at the same time open-circuiting and restoring relays D2' and DE'.

Relay D2', at its contacts 4, disconnects energizing potential from'conductor DC I, thereby removing marking potential from all of the keys in column 2I3 of KSl', thereby removing the impulse counter from under the control of the keys in this column. At its contacts 4, relay D3' applies energizing potential to conductor DC2, extending to the upper contacts of the keys in the seconddigit column 2M of KSI, whereby the impulse counter is placed under the control of the keys in such column. With key 5 in this column operated, the operating potential is further extended to conductor 5 in cable CAI, and thence through contacts of relay CI and mark conductor M5, to the upper winding terminal of relay I I of the impulse counter.

The cycle of operations of the impulse counter described in connection with the transmission of the first recorded digit 5 is'now repeated, during which the five impulses corresponding to the second recorded digit 5 are transmitted over conductors X", Y', and Z' to the repeating relay RR.

IIA?. Transmitting the third recorded digit 5 When relay IB' ungrounds conductor XI" at the end'of the transmission of the secondrecorded digit, digit-counter relay D3' remains operated, and control relay DO' operates, in the following locking circuit, effective only if the number potential.

ing relay Il. the consequent regrounding ofvconductor XI' closes a circuit through contacts of the restored relay DE' for counting relay Dt', supplied with operating potential through contacts I of relays D3' and DO. At its contacts I, relay Dd' locks operating potential on its upper winding terminal, at the same time open-circuiting and restoring relays D0 and D3'.

By opening its contacts d, relay Dt removes operating potential from conductor D82, thereby removing the impulse counter from under the controll of the second-digit column 2id of key set KS 'At its contacts .2, relay Dil' applies operating potential to conductor DCB (digit controlthird), extending to the upper contacts of the third-digit keys, column 2l5 of KSI', whereby the impulse counter is placed under the control of the keys in such column. With key 5 in this column operated, thel operating potential is further extended to conductor 5 in cable CAl, and thence, through contacts of. relay CI' and over mark conductor M5, to the upper winding terminal of relay II' of the impulse counter.

The cycle of operationsv of the impulse counter described in connection with the transmission oi the first recorded digit 5 is again repeated, during which live impulses corresponding to the third recorded digit 5 are vtransmitted over conductors X', Y', and Z' to the repeating relay RR.

lIAB. Repeating the number transmission When relay I0 of-the impulsel counter operates v at the end of the transmission of. the third recorded digit 5 to unground conductor XI', relay D4' vimmediately restores, not having locked operated independent of conductor XI The res-V toration of relay D4' clears out the digit counter, returning it to its illustrated normal condition.

The impulsecounter is cleared out and returned to normal condition upon the termination of the instant impulse over conductor 26|, following which operations as described recur` so long as start conductor 200 remainsJ grounded, to hold v start relay ST grounded.

IIA9. Clearing out When the non-locking release key R' at key chain relay CI'. Consequently, lamp 2| 6 becomes extinguished, and relay CI' restores, opening the connection between its right-hand winding and that of relay CC'. Relay CI' also disconnects conductors ST, 5 to I, L2', and L3' -in cable CAI from the corresponding common conductors, terminating the individualizatio'n of the system with key set KSI The described restoration of relay CI', by disconnecting conductors ST and 208, removes the ground connection initially applied to start conductor 208. Since this operation occurs while relay DI is operated, relay ST' is not then locked locally, for start conductor 208 is disconnected from ground-supply conductor 209. Start relay ST' accordingly restores and ungrounds con' ductor 209, thereby terminating operation of the ductor M5.

IIB. calling ome! s dfgn numbers I v Any desired 3-digit number other than the previously assumed number 555 may be set up on the key set KSI'. For example, if the ilrst digit of the called number is 4, key 4 of column 2I3 is' operated instead of key 5. In this event, when digit-control lead DCI is energized, energizing potential is transmitted (over conductor! of cable CAI and through contacts of relay CI') to mark conductor M4. instead of to mark con- Mark conductor Ml extends to the upper winding terminal ot the second counting relay I2' of the impulse counter, whereby relay I2' is initially operated instead of relay II', at the beginning of the transmission of the iirst recorded digit. As a result, one less impulse is 24 Relay D2' Laccordingly transmission oi the ilrst recorded digit, starting a new cycle oi' operations at that point.

III. From 3 IIIA. Calling a B-digit number The operation oi the apparatus shown in'FIg. 3 (a modification of the register portion oi.' Fig. 2) will now be described. For this DUIPOSG. it Will be assumed that the operator at control station CSI desires to transmit a 3-digit called number. It will |be recalled that Fig. 3 is a modiilcation oi Il portion of Fig. 2 lying below broken line mai. individualism@ :he system with control Station CS1 The system must first be individualized with-the circuit for the lower winding of relay CIn by way required to operate the impulse counter through I the shortened cycle of operations. resultingin only four impulses being transmitted to the re- Q circuit for itself over conductor 301, in series with l peating relay'. Similarly, mark conductor M3 is 30 the vone energized if key 3 is the one operated in column 2I3, whereby the cycle of operations of the impulse counter is further shortened in that relay I3' is the one initially operated.

If the second key in column 2II is the one operated, markv conductor M2 is the one energized, resulting in the initial operation of counting relay I4', in which case only two impulses are transmitted to the repeating relay.

Finally, if key I of column 2H is operated, mark conductor MI is the one energized, resulting in the initial energization of relay I5' of the impulse counter, in which event only a single impulse is transmitted to the repeating relay as the first recorded digit.

Similarly, the second and third recorded digits may have any value of from 1 to 4 instead of the described value of 5, provided the correspondingkeys are operated in columns 2| 4 and 2 I 5 of KS I IIC. Calling Z-digit numbers Ii' the number being called contains only two digits, the operator at key set KSI' actuates the desired keys in columns 2 Il and 2M, and restores any key which may be actuated in column 2I5.

Locking conductor L3' in cable CAI is accordingly not grounded, wherefore locking conductor L3 is not grounded. In this event, counting relay D3 of the digit counter cannot lock operated o Y IID. Calling single-digit numbers When a single-digit number is to be called, the

oi' conductor 350, contacts oi relay CC. and

thence by way of guard conductor 2.1 to the source of operating poten'tial as shown in Fig. 2.

Relay CI2 now operates and prepares a locking cham-control relay CC. This locking circuit is maintained open for the time being until impulse relay IMP operates.

At its lo'wer contacts, relay CI2 closes a circuit for impulse relay IMP: Froml ground through the normally closed impulse contacts of the callin! device CD, signal lamp SIS, lower contacts of relay CI, the winding of relay IMP, to the operating potential. Relay IMP thereupon operates to break connection with impulse conductor 302, preparatory to impulse transmission. Relay IMP also connects the upper winding terminal of chaincontrol relay CC to locking conductor 301, thereby completing the prepared locking circuit for the upper winding of'relay CI2. Relay CO2 thereupon operates in the noted locking circuit. At its upper contacts, it connects the grounded conductor 303 to the upper armature of relay IMP; at its inner upper contacts. it shunts the corresponding contacts of relay IMP to maintain the locking circuit intact during the impulsing operation; at its inner lower contacts, it disconnects guard conductor A201 from conductor 350, rendering relay CI? dependent on its locking circuit; and at its lower contacts, it grounds conductor 300, thereby energizing the lower winding (the holding winding) o! control magnets 304 to Ill of registers RI and R3 respectively. No immediate cooperational eil'ect is produced by the energization of these holding windings.

With relays IMP and CC2 operated, the receiving circuits are now conditioned for the setting operator at key se't KSI' operates the desired key 70 of the rst register RI This fact is indicated to the operator by the glowing of signal lamp SIB in series with relay IMP. IIIA2. Transmitting and recording the ilrst digit times,` each time opening the previously traced circuit for relay IMP. e

Relay IMP momentarily restores each time its circuit is opened at the calling device CD. Each restores at the end of the f operate winding eg time it does so, it connects the grounded con ducto: 3533 with'conductor 3ds, thereby cig a circuit, through contacts of transfer relay IR-5,.

ister contacts i. The od-n -n- :.5 contacts remain closed thereafter until the register is cleared out.

l In the event that the transmitted vimpulse series contains further impulses, the receipt of the second impulse by the operate winding of magnet 303 results in the closure ofthe second'setof register contacts 2, preceded slightly by the opening of contacts i. That is, upon the closure of any of the .register contacts 2 toil of the lregister Ri, the preceding register contacts open just before the new closure is eected. By the operation now being described, one or another of the marking leads Ml, to M5 of the register Rl is oonnected to the first-digit control lead DCI, preparatory to the transmission of the rst recorded digit,

With olf-normal contacts ON of the register Rl closed, on each reoperation of relay IMP, ground is extended to the lowerY winding terminal of transfer relay TRI: from the grounded upper armature of lrelay IMP, conductor off-normal contacts ON of register RI, and the normally closed contacts controlled by the lower armature of relay 'IRi Relay 'I'RI is so wound and adiusted that it does not operate during the vibratory action of relay IMP while the remaining impulses of the series are being transmitted. But, relay 'IRI operates when relay IMP comes to rest, inA operated condition, at the end of the impulse series. At its lower armature, relay 'I'RI locks itself directly to the grounded conductor Transmitted' the recorded number i of the recorded number iby the above the brokenline 3 3 of uw a: to the grounding ci start conductor 263, effected bythe upper ns1-y digit blank; digit-contrer read not is enersized. marmng potential is thereby extendedv through' the closed 'pair of register contacts of fthe register Ri to theconcerned one of the mark 300, at the same time opening its initial operating circuit. At its inner upper armature, relay TRI 1 disconnects conductor 302 from the operate winding of magnet 300 of the register RI and transfers it to the corresponding winding of magnet 303 of the register R2, preparingthe register R2 to receive the second transmitted digit in the number being called. y

When the calling device CD is operated in accordance with the second digit in the desired number, the resulting impulses transmitted over conductor 302 by relay IMP are delivered, through contacts of the operated relay TRI and contacts of the unoperated relay TR2, to the operate winding of magnet 303. The register R2 operates as described forthe register RI, connecting one or another of the mark leads MI to M5 to the second-digit control conductor DC2, according to the value of the called second digit.

When relay IMP comes to rest in an energized condition at the end of the second digit, transfer relay TR2 (having characteristics similar to those of TRI) operates over conductor 30| and through off-normal contacts of the second register. Upon operating, relay TR2 locks itself directly to conductor 300, and transfers impulse conductor 302 from the operate windingrof the second register to the operate winding of magnet 306 of the third register R3. Accordingly, register R3 responds as described for the registers RI and R2 and records the value of the thirdv digitv by connecting the thirddigit conductor DC3 to one or another of the mark leads MI to M0.

leads Mi to M5. thereby causing the impulse counterA of Fig. 2 to'transmit'the rst 'digit of the worded value. Similarly, when the energizing potential is transferred irom conductor DCi to EQ2, one or another of thefmark leads Ml to ME is. energized depending upon the setting of the register R2, causing the second transmitted digit to have a corresponding value. Finally, whenV the energizing potential is transferred to digit control conductor DC3, one or another of the mark leads MI to M5 is Supplied with energizing potential according to the setting of the register R3,v causing the third transmitted digit to have a.v value corresponding to such setting.

The fac that a second digit has been recorded is indicate to the digit counter of Fig. 3 by the application of ground potential to locking conductor L3 at the upper contacts of second transfer relay TR2. The fact that a thirdl digit has been recorded is indicated to the digit counter of Fig. 3 by the grounding of locking conductor L3 at the od-normal contacts of the register R3.

IIIA4. Clearing out When the recorded number has been transf mitted a desired number of times, the operator at control station CSI may initiate the clearingoutoperation by momentarily actuating the non- -locking release key R2. Operation of this key grounds conductor 301, thereby short-circuiting the upper winding of chain relay CIZ. Relay CI thereupon restores. At its upper contacts, relay CI2 ungroundsconductor 303, thereby preventing the transmission of a further impulse over conductor 302 upon the restoration of relay IMP, which occurs responsive to the opening of the lower contacts oi relay Cl.

Lamp 3|3 becomes extinguished responsive to the opening of the lower contacts of relay cl2, notifying the operator that the release key R2 may be restored. Upon the'restoration of key R2, chain-control relay CC2 restores. At the lower contacts of relay CC, the ground connec tion initially made to conductor 300 is opened, leaving this conductor grounded, if at all. by way of start conductor 208. If start conductor 208 is grounded, as it is vwhen the impulse-sending apparatus is in any position other than its digit-blank position, conductor 300 is thereby maintained groundedto hold relays lI'RI and TR2 operated. along with the registers RI to R3. i When the sending apparatus next reaches its digit-blank position, and start conductor 208 becomes ungrounded, conductor 300 is consequently ungrounded, permitting relays TRI and TR2 to restore. At the same time, the -hold windings of magnets 304 to 306 are open-circuited, permitting the registers Rl to R3 to clear out. The restoration of start relay ST' of Fig. 2, occurring responsive to the ungrounding of conductor 203, Yreapplies Apotential to guard conductor 201.

digit from -the con- When, olfiowing transmission of the preliini?y 

